Diagnostic Test Unit - User Operating Problems
CATEGORYTools/Maintenance
SECTION
1
PAGE
25
ISSUE
11/92-0269
CODE
101
Subject:
ISAT with EPROM M93 - User Problems
Application:
900, 9000
A few questions and problems have surfaced concerning EPROM version 3.12 (M93) for the ISAT, Figure 1. Following is a list of problem areas and some temporary measures to use until these items have been resolved. This bulletin will be superseded at that time.
1. SDA (Saab Diagnostic Adapter)
2. ETS Condenser cable
3. The ISAT "MEASURE" function
4. Saab TRIONIC engine management system
5. Diagnosis of car electronics (green socket)
6. Command codes in LH 2.4.1 and LH 2.4.2
7. Limited command code activation time
8. Keypad operation
Action:
Each problem area listed above is defined in detail and if applicable, the operation procedures are given.
1. SDA (Saab Diagnostic Adapter), Figure 2
Using an ISAT with EPROM M93 (version 3.12) requires connection of the SDA to the instrument. If communication problems with a system other than TRIONIC (e.g., ACC) occurs, removing the SDA from ISAT should be tried.
2. ETS Condenser Cable, Figure 3
Using an ISAT with EPROM M93 (version 3.12) always requires the use of a Capacitor Cable, P/N 86 11 048, in connection with diagnosis of the engine system (black socket).
The reason for this is that the current or voltage transients that are generated must be electrically isolated from the ISAT to avoid faulty operation. Use of the SDA does not ensure a sufficient degree of filtering.
3. The ISAT "MEASURE" Function
Using an ISAT with EPROM M93 (version 3.12) always requires connection of the diagnostic or TSI cable when the "MEASURE" function (F3) is activated in the diagnostic mode.
With EPROM version 3.12, ISAT receives its power supply from the diagnostic or TSI cable, Figure 4. If one of these cables is not connected, the display will go out on activation of "MEASURE" and the function will not be performed.
ISAT, TSI Cable 86 10 727
ISAT Diagnostic Cable 86 10 701
4. Saab TRIONIC Engine Management System
Using an ISAT with EPROM M93 (version 3.12) involves the following when entering command codes:
Command Code EE30 (display throttle position) - On U.S. specification cars, this command can only be used with the engine running.
Command Codes EE00-EF46 - The TRIONIC software always gives priority to the function while the diagnostic program runs in the background.
If the above codes are used while the engine is running, the engine may occasionally stumble or stall due to the amount of diagnostic data being transmitted from the TRIONIC ECM to ISAT. In most cases the engine will restart immediately. If the engine does not want to start, clear the system by entering Command Code FF00.
Command code EE40 - The reading should always be multiplied by 10 to obtain the correct level. For example, if the display shows 80 mV it should be multiplied by 10 to obtain the correct figure of 800 mV.
5. Diagnosis of car electronics (green socket)
Using an ISAT with EPROM M93 (version 3.12) may result in communication problems with the car's other electronic systems (green socket).
This is because the ACC system's diagnostics protocol does not conform to current standards on some important points. This not only affects communication with the ACC system but unfortunately also with the car's other electronic systems.
In the case of persistent trouble, the ACC control module fuse (# 1) must be removed. Diagnosis of the car's other electronic systems can then be carried out.
6. Command codes In LH 2.4.1 and LH 2.4.2
Using an ISAT with EPROM M93 (version 3.12) may result in a breakdown in communication with the LH 2.4.1 and LH 2.4.2 systems when any of the following command codes are used:
22A - 22B - 23A - 239 - 249 - 250 - 279
This is because these command codes are not incorporated in all LH control module software.
In the case of a communication breakdown, communication between the ISAT and the LH system in question must be re-established.
7. Limited command code activation time
To avoid glitches in the display function (display freezing), the time during which a command code is activated should not be longer than absolutely necessary.
If the display does freeze, press ESC (escape). Repeat a few times, if necessary. If that doesn't work, unplug the ISAT diagnostic cable followed by the internal battery. Once the screen goes completely blank, reconnect the power supply and the ISAT diagnostic cable. NOTE: This problem primarily occurs when working with the TRIONIC system.
8. Keypad operation, Figure 5
Difficulty in establishing communication with a system may be due to any of the problem points 1-7 above. An additional cause could be that keystrokes are not immediately processed by the ISAT.
To give the ISAT sufficient time to process keystrokes, the keys should be held down for a moment after the "click" which verifies that the key has been properly depressed.